Various stacker tray devices are known for the purpose of receiving and stacking sheets of paper exiting the usual office printer or copier wherein the receiver tray is adapted to be moved downwardly by relatively complex sheet detecting and stack height detecting mechanical drive systems.
In addition, various offsetting mechanisms are known for purposes of enabling a stacker tray, or other trays such as in sheet sorting machines, to receive sets of documents on the tray but positioned in offset relation to one another so as to facilitate set separation.
Detection of stack height and lowering of the stacker tray is shown, for example, in U.S. Pat. No. 5,350,169 granted Sep. 27, 1994.
Offsetting of the sheet sets has heretofore been accomplished in a number of ways including relatively angularly displacing the sets as shown in U.S. Pat. No. 4,382,592 granted May 10, 1983, by gripping a sheet between feed rolls which are shifted transverse of the direction of sheet feed. As shown in British patent 1256289 published Dec. 8, 1971 the sheet gripping rolls are shifted by a cam mechanism between a center position and alternate positions left and right of center.
In addition, in IBM Technical Disclosure Bulletin Vol. 17 No. 8 dated Jan. 8, 1975, at page 2255 there is disclosed a sheet stacking platformto which sets of sheets are supplied by a sheet feeder wherein the platform is supported for movement transverse of the sheet feeding direction upon rotation of a cam so as to offset the sets of sheets.